Constructing heterojunctions by surface sulfidation for efficient inverted perovskite solar cells

A stable perovskite heterojunction was constructed for inverted solar cells through surface sulfidation of lead (Pb)-rich perovskite films. The formed lead-sulfur (Pb-S) bonds upshifted the Fermi level at the perovskite interface and induced an extra back-surface field for electron extraction. The resulting inverted devices exhibited a power conversion efficiency (PCE) >24% with a high open-circuit voltage of 1.19 volts, corresponding to a low voltage loss of 0.36 volts. The strong Pb-S bonds could stabilize perovskite heterojunctions and strengthen underlying perovskite structures that have a similar crystal lattice. Devices with surface sulfidation retained more than 90% of the initial PCE after aging at 85 degrees C for 2200 hours or operating at the maximum power point under continuous illumination for 1000 hours at 55 degrees +/- 5 degrees C.

Automated summary

A stable perovskite heterojunction was achieved in inverted solar cells by sulfidating the surface of lead-rich perovskite films, resulting in improved power conversion efficiency and open-circuit voltage.